如何从ARGB计算窗口颜色？

Question

谁能告诉我如何从ARGB中计算出相应的窗口颜色？我知道有一个ColorTranslator.ToWin32()来进行计算，但是它是如何完成的呢？

另外，OLE颜色和窗口(win32)颜色之间的区别是什么？

JD.

Answer 1

.NET中的颜色对象包括alpha通道(即透明度级别)，而Win32颜色则是纯RGB。因此，要在两者之间进行转换，您需要类似于以下内容：

    static public int ConvertColourToWindowsRGB(Color dotNetColour)
    {
        int winRGB = 0;

        // windows rgb values have byte order 0x00BBGGRR
        winRGB |= (int)dotNetColour.R;
        winRGB |= (int)dotNetColour.G << 8;
        winRGB |= (int)dotNetColour.B << 16;

        return winRGB;
    }

    static public Color ConvertWindowsRGBToColour(int windowsRGBColour)
    {
        int r = 0, g = 0, b = 0;

        // windows rgb values have byte order 0x00BBGGRR
        r = (windowsRGBColour & 0x000000FF);
        g = (windowsRGBColour & 0x0000FF00) >> 8;
        b = (windowsRGBColour & 0x00FF0000) >> 16;

        Color dotNetColour = Color.FromArgb(r, g, b);

        return dotNetColour;
    }

Answer 2

使用IL反汇编程序(如Reflector)，您可以获得ColorTranslator.ToWin32()的代码。请注意，ToWin32颜色不使用Alpha值。

public static int ToWin32(Color c)
{
    return ((c.R | (c.G << 8)) | (c.B << 0x10));
}

ColorTranslator.ToOle(...)正在测试颜色是否为标准系统颜色，否则将使用ToWin32转换：

public static int ToOle(Color c)
{
    if (c.IsKnownColor)
    {
        switch (c.ToKnownColor())
        {
            case KnownColor.ActiveBorder:
                return -2147483638;

            case KnownColor.ActiveCaption:
                return -2147483646;

            case KnownColor.ActiveCaptionText:
                return -2147483639;

            case KnownColor.AppWorkspace:
                return -2147483636;

            case KnownColor.Control:
                return -2147483633;

            case KnownColor.ControlDark:
                return -2147483632;

            case KnownColor.ControlDarkDark:
                return -2147483627;

            case KnownColor.ControlLight:
                return -2147483626;

            case KnownColor.ControlLightLight:
                return -2147483628;

            case KnownColor.ControlText:
                return -2147483630;

            case KnownColor.Desktop:
                return -2147483647;

            case KnownColor.GrayText:
                return -2147483631;

            case KnownColor.Highlight:
                return -2147483635;

            case KnownColor.HighlightText:
                return -2147483634;

            case KnownColor.HotTrack:
                return -2147483635;

            case KnownColor.InactiveBorder:
                return -2147483637;

            case KnownColor.InactiveCaption:
                return -2147483645;

            case KnownColor.InactiveCaptionText:
                return -2147483629;

            case KnownColor.Info:
                return -2147483624;

            case KnownColor.InfoText:
                return -2147483625;

            case KnownColor.Menu:
                return -2147483644;

            case KnownColor.MenuText:
                return -2147483641;

            case KnownColor.ScrollBar:
                return -2147483648;

            case KnownColor.Window:
                return -2147483643;

            case KnownColor.WindowFrame:
                return -2147483642;

            case KnownColor.WindowText:
                return -2147483640;

            case KnownColor.ButtonFace:
                return -2147483633;

            case KnownColor.ButtonHighlight:
                return -2147483628;

            case KnownColor.ButtonShadow:
                return -2147483632;

            case KnownColor.GradientActiveCaption:
                return -2147483621;

            case KnownColor.GradientInactiveCaption:
                return -2147483620;

            case KnownColor.MenuBar:
                return -2147483618;

            case KnownColor.MenuHighlight:
                return -2147483619;
        }
    }
    return ToWin32(c);
}

这意味着如果声明color Color = SystemColors.ControlText，颜色( ColorTranslator.ToOle )将返回-2147483630，但如果将颜色设置为自定义ARGB颜色，ColorTranslator.ToOle将返回标准ToWin32()值。